U.S. Pat. No. 3,949,621 discloses a driving belt of substantially trapezoid-shaped cross section for use with pulleys having V-shaped grooves, the belt being constructed of an endless carrier in the form of at least one metal band on which are slidably mounted a plurality of plate-like elements each disposed transverse to the carrier and each being in face-to-face contact with the two adjacent elements. One face at the inner end portion of each element is bevelled or tapered away from the adjacent element for enabling the bending of the driving belt whereby each transverse element contacts each adjacent element along a tilting line which is located where the bevel merges into a surface which is parallel to the opposite face. Near their outer ends the transverse elements are fitted with coupling means in the form of at least one projection on one face and a substantially corresponding recess in the other face, the projection on one element engaging the recess in an adjacent element.
In such a driving belt power substantially is transmitted by pushing forces between the transverse elements. The projections and recesses serve to center the transverse elements relative to each other. Such centering may be desirable for preventing the transverse elements in the straight parts of the driving belt from shifting relative to each other.
However, it has been established experimentally that a slight mutual shift possibility of the transverse elements is desired as long as the transverse elements are present in the pulley, since each transverse element should have the freedom to be clamped optimally between the flanges of the pulley. Also in the parts of the belt between the pulleys there should be a slight shift possibility in case of slight alignment errors of the pulleys, such as those which occur in particular with pulleys of the kind in which the mutual distance between pulleys is changed for varying the transmission ratio. The pulleys then do no lie exactly in one flat plane, so that a kind of torsion may occur in the driving belt.
U.S. Pat. Nos. 3,720,113 and 4,080,841, Swiss Pat. No. 256918 and German Offenlegungsschrift No. 2,414,989 also disclose driving belts having tiltable transverse elements.